from knowledge import * 

x = Event(
  name="a terrible tragedy",
)
print type(x)
y = Person(
  name="Bond, James Bond",
  birth=Event(
    name="the birth of 'none'",
    when=Date(1564, 3, 4)
  ),
)
x.instigators.add(y)
print [str(i) for i in x.instigators]
print x.instigators.pop().birth.start
print [str(i) for i in x.instigators]
